1. Field of the Invention
This invention relates, generally, to tools used in radiology. More particularly, it relates to a biopsy tool that helps radiologists using imaging techniques such as ultrasound or CT scanning to properly align a guide needle relative to a lesion or tumor in a breast or other soft tissue.
2. Description of the Prior Art
One commonly used biopsy tool is a spring-loaded, trigger-operated device that shears off and captures a tissue sample from a lesion or tumor so that the sample can be analyzed in a lab. A guide needle is first inserted into a breast or other soft tissue where a lesion is detected, using a preselected imaging technique such as ultrasound or CT scanning, so that the physician can see the guide needle and the lesion. The longitudinal axis of the guide needle is aimed directly at the lesion, and the distal end or tip of the guide needle is placed in close proximity to the lesion. The proximal end of the guide needle remains external to the breast or other soft tissue.
If the guide needle appears to be properly positioned relative to the lesion, the leading end of the biopsy tool is then inserted into the bore of the guide needle at its proximal end. When the trigger is pulled, the operative part of the biopsy tool extends quickly, under the bias of its propulsion spring, from the open distal end of the guide needle, enters into the lesion, shears off a tissue sample, captures the sheared off sample in a small compartment, and retracts. The physician withdraws the biopsy tool from the guide needle, removes the sample from the compartment, and re-introduces the tool into the guide needle for the taking of an additional sample. A physician will typically take four of five such samples in sequence to ensure that different parts of the lesion have been sampled and to provide sufficient tissue for the testing lab. Using the guide needle requires but one entry into the breast or soft tissue and allows multiple entries of the biopsy tool through the hollow bore of the guide needle.
There are several drawbacks to this well-known procedure. First of all, it is difficult to see the guide needle under ultrasonic, CT scanning, and other types of imaging. If the guide needle is improperly positioned with respect to the lesion, the spring-loaded biopsy tool inserted thereinto will be equally mis-positioned and the tissue-shearing mechanism will miss the lesion when the trigger is pulled. The guide needle has a rather large bore to accommodate the biopsy tool, so the patient is not pleased when it has to be withdrawn and re-inserted so that the physician may try to hit the lesion again.
Nor does the art provide any means for preventing migration of the guide needle after it has been successfully positioned in an optimal relationship with a lesion or tumor. Thus, if a patient has had to endure numerous guide needle re-entries until it is finally properly positioned, a migration of the needle tip away from the lesion can still result in a missed biopsy because the shearing mechanism of the biopsy tool may fall short of the lesion and shear healthy tissue.
What is needed, then, is a means for enhancing the visibility of the guide needle under ultrasound, CT scanning, or other imaging technique. If such a means could be found, it would ensure proper alignment and optimal placement of the guide needle relative to a lesion or tumor and thus would ensure consistent hitting of the lesion by the shearing mechanism of the spring-loaded biopsy tool. Repeated insertions of the large bore guide needle would then become unnecessary.
A means for anchoring the guide needle into position after it has been optimally positioned is also needed.
However, it was not obvious to those of ordinary skill in this art how the needed means could be provided, in view of the art considered as a whole at the time the present invention was made.